Raise Spectre can gain the benefits of many different types of support gems, but not all of them may be beneficial depending on the type of Spectres raised. Support gems that increase Attack Speed or modify physical damage won't be useful on caster monsters. Support gems that modify projectiles or spells won't have any benefit for melee Spectres. Minion-specific support gems will work on every type of Spectre to varying degrees of success. (http://pathofexile.gamepedia.com/Raise_Spectre).